Tire casing spreader



July 29, 1941. G. l. ANDERSON TIRE CASINGSPREADER Filed Feb. 3. 1939 9 vSheets-Sheet l a I/' 5253 #54 55- 46' 3 4 42e lf .53 I/ .3o JZ /08 I 5?Ja 3 v `f2 J5 f vejnza/ 'zzJZaz'Jjnonsaf] MM2/mw July 29, 1941- G. 1.ANDERSON 2,250,740

TIRE cAs ING SPREADER Filed Feb. 5, 1939 9 Sheets-Sheet 2 July 29, 1941.G. l. ANDERSON TIRE CASING SPREADER Filed Feb. v5, 1959 9 Sheets-Sheet 5July 29,1941. G. l. ANDERON 2,250,740

TIRE CASING SPREADER Filed r'eb.- s, 1959 9 sheets-sheet 4 l 34 www July29, 1941. G. ANDERsoN 2,250,740

- TIREv cAsING SPREADER Filed Feb. 5. 11939 QAShQetS-Sheet 5 July 29,1941. G. ANDERSON TIRE CASING SPREADER 9 Sheets-Sheet 6 Filed Feb. 3, 1939 July 29, 1941. G. l. ANDERSON TIRE CAS ING SPREADB Filed Feb. 3.1939 9 sheetsJ-sheet '7 July 29, 1941. G. l. ANDERSON TIRE CASING sPREADER Filed Feb. 3. 1939 GZUZ-uj [denron 9 Sheets-Sheet 3 July 29,1941. l G, l. ANDERSON 2,250,740

TIRE CASING SPREADER Filed Feb. 3, 1939 9 Sheets-Sheet 9 jnenior 23zzsaz) [ndenson Patented July 29, 1941 UNITED STATES Q PATENT OFFICETIRE CASING SPREADER.

Gustav I. Anderson, Minneapolis, Minn., assignor to Ke HawkeManufacturing Company, Minneapolis, Minn., a corporation of MinnesotaApplication February 3, 1939, Serial No. 254,412

19 Claims. t (Cl. 154-9) This invention relates to devices generallyknown as tire casing spreaders, and generally stated has for its objectto improve the same in respect to mechanical construction and operationsfor rapid and eflicient work, in the handling of modern or present daytires, in inspecting and repairing tire casings.

Particularly, the invention provides a tire spreader that is adapted tohandle very large and very heavy tire casings such as now used ontrucks, tractors and the like. These large tire casings frequently weighas much as two or three hundred pounds or even more, and the handlingand spreading of such casings require not only strong but powerfulmechanism, in which the several necessary operations of the machinecannot be performed rapidly or with commercial efflciency by manualpower and, hence, requires mechanical motive power.

In this improved machine there is employed fluid pressure motors,preferably cylinder and piston air actuated structures, which arecombined with casing manipulating devices of novel construction andrelative arrangement, whereby the largest and heaviest casing, as wellas lighter ones, can be handled, spread and inspected with that ease andrapidity required for commercial success and economy.

A commercial form of the machine is illustrated in the accompanyingdrawings wherein like characters indicate like parts throughout theseveral views.

Referring to the drawings:

Fig, 1 is a perspective of the complete spreader as viewed from thefront thereof, showing the initial condition of the tire applied inposition for spreading;

Fig. 2 is a view corresponding to Fig. 1 but showing the spreader andtire after the initial movement of the spreader has been performed.

Fig. 3 is a perspective of the spreader with a portion of the supportingbase removed and with the parts viewed from the rear'of the spreader;

Fig. 4 is a perspective with parts broken away showing the spreader headand associated parts on a larger scale than in Figs. 1 and 2;

Fig. 5 is a view similar to Fig. 4 but with some parts omitted andillustrating the different positions of the parts from that shown inFig.V 4;

Fig. 6 is a perspective of most of the parts l shown in Fig. 4 viewedfrom the rear;

Fig. 7 is a perspective partly in section and partly in full showingparticularly the construction and arrangement of the air actuated motor,

the parts primarily actuated thereby and connection to valve mechanismfor controlling the motor operations;

Fig. 8 is a detail in vertical section taken on the line 8 8 of Fig. '7;

Fig. 9 is a perspective showing the body of the control valve structurelooking at the face thereof;

Figs. 12, 13, 14 and 15 are views corresponding to Fig. l1, butillustrating step operative positions of the valve;

Figs, 11a, 12a, 13a, 14a-and 15a are perspective views showing the valveoperating connections in by step different lpositions correspondingrespectively to Figs. 11,

12, 13, 14 and 15;

Fig. 16 isa view in side elevation illustrating the various positions ofthe control lever which operates the control valve.

The supporting frame for the entire machine is preferably in the form ofa column or heavy post 20 having a spider-like base'2l. Formed as a partof or otherwise rigidly secured to the upper end of the column 20 is ahead plate 22 formed with a centrally located hub 23, best shown inFigs. Zand '7. Again as best shown in Fig. 7, the laterally spacedhorizontally disposed cylinders 24 are rigidly secured to and at theirfront ends are closed by the head plate 22. Rigidly secured to andclosing the rear ends of the cylinders 24 are cylinder heads 25 which,in turn, are rigidly secured to a rear vhead or bearing plate 26'.

Mounted to slide through the hub 23 of the front head plate 22 andthrough the central portion of the rear head plate 2B is a primarythrust bar ,or slide 2l. Asrshown in Fig. 4 the hub 23 is provided witha roller 28, and as shown in Fig. 7 the rear head plate 26 is providedwith rollers 29 to reduce Ivthe friction between the primary thrust bar21 and the said head plates.

At itsv extreme front and the primary thrust bar V2'! terminates in'atrunnion 21 on which is rotatably mounted a hub 30'having radial arms3Q', to the outer ends of which is rigidly secured an annular bearinghead 3|, see particularly Figs. 4, 5 and 6.` Rigidly secured on thetrunnion 2l just outward of the hub 30 is a retaining collar 32. Thisbearing head 3l is provided with outstanding guide sleeves `33, as shownfour in number,` located apart; and mounted in the plungers 34.

guide sleeves 33 to move radially in respect to the axis of the hea-d 3lare grapple projecting These plungers 34, at their outer ends, arerigidly secured to sleeve-like heads 35. Extended through the heads 25both forwardly and rearwardly therefrom are grapple carrying rods 36 onwhich the sleeve-like heads freely slide. rFriese rods 36 arehorizontally disposed and are parallel and are located 90 apart; and

, at their rear ends the rods are secured to the outer ends ofadjustable arms made up of overlapping bars or members 31 and 38. Theinner ends of the bars 38 are secured to a hub. 39, see particularlyFigs. 3 and 4, that is rotatable on a trunnion 40, that is a fixed partof the hub 23,

Sliding movements of the bars 31 on the bars 385 is permitted andcontrolled by slots 4l in the former and hea-ded screws 42, or the like,thatv work in said slots and are secured to the barsV 38'. Rigidlysecured to the extreme front ends of the grapple-carrying rods 36 arecapping brackets 43 having outstanding lugs' that are tied tooutstanding lugs on the extreme outer ends of the bars 31, by tie rods44,'best shown in Fig. 3.

Inner hook-like grapplesA 45 are rigidly secured to the sleeves 35 and`to the plunger-acting rods- 34, and project radially inward andterminate in hook-like ends for engagement with the inner surfaces ofthe beads of the tire casing. In the drawings Figs. 1, 2 and 3, the tirecasing is indi-- cated as anV entirety by the character T.

Companiongrapples 46, similar to the grapples 45, are pivotallyconnectedito lugs on the capping brackets 43 at 41. These grapples 46have stop projections 48 that engage the brackets 43v and limit themovements of the grapples 46 towards the relatively fixed grapples 45.The grapples 46 are yieldingly held in position, best shown in Figs; 1,2 and` 3, by coil springs 49 attached thereto and to the respectivebrackets 43.

In the construction so far describedthe grapples 46 are fixed againstmovement longitudinally of the primary thrust bar 21 and of the axisofthe rotary structure made up of the annular bearing` head 32, the arms31 and 38, andthe parts *carriedthereby. The annular bearing 32,

plungers 34, and the sleeve-like heads 35 and grapples 45, are, however,movable toward and from the grapples 46 under sliding movements of theprimary thrust bar 21; and these relative movements of the grapples 45,the one away from the other, function in spreading the tire casing, allaswill be hereinafter more fully'k described.

Simultaneous movements of the grapples 45 and 46 toward the axis of thetire casing and of the primary bar 21 are produced by ,novel mechanismwhich will now be particularly described. As an important element forthe purpose just noted, there is provided a secondary thrust bar 50which, as shown, is mounted to slide in a longitudinal groove formed-'inthe p'rimary bar 21. Mounted to slide on the primary bar 21 and xed tothe secondary bar 50 for sliding movements therewith is a groovedcollarIa in the. groove of which is swiveled a platelike thrust head 5l andwhich, as shown, has outstanding armsv or projections, see particularlyFig. 6. The arms or projections ofA this thrust head 5I are connected bylinks 52 to the elbows or intermediate portions of bell crank levers 53and by means of pivot pins 54, see particularly Figs. 3, 4, 5 and 6, tohinge lugs or projections 55 on the front face of the annular bearinghead 32. Preferably, and as shown, these bellV crank levers 53 are madein duplicate by laterally spaced bars that straddle the arms 3l of thehub 30. These bell crank levers, as will be noted, extend throughopenings in the bearing head 32, and their rear arms are pivotallyconnected, see particularly Fig. 6, by pivot pins 56 to the inner end oflinks 51, the outer ends of which work through slots 56 in the backs ofthe guide sleeves 33 of the bearing head 32 and are pivotally connectedat 59 to the plungers 34.

In the construction just described, when the secondary thrust bar andits head 5l are moved rearward, the plungers 34, and hence the grap-V.ples 45v and 46, will be moved radially outward and conversely whensaid thrust bar 50 and its head 5l are moved forward, the plungers andthe grapples will be moved radially inward or toward the axis of therotary part of the device.

The cylinders 24' heretofore noted constitute elements of a pair of twinair motors that afford the power for performing the various operationsofthe tire spreader. Within each of these cylinders, see particularlyFig. 7', are two pistons 60- and; 6l; The pistons 60 have tubular rods.or stems 62 that work through the respective cylinder heads 25, thebearing plate or head 26; and the pistons 6l Ihave stems 63 that workthrough the tubular piston rods or stems 62. At their projecting endsthe tubular piston rods 62 are tied together and' rigidly secured to theprimary thrust thrust bar 21 by a cross head 64; and the projecting endsof the piston rods 63 are tied together and secured at 65 to the rearend of the secondary thrust bar 50 by a cross head 66 that slides freelyon the primary bar 21. The crossyhea'd 64'. is shown as rigidly butadjustably secured to the primary bar 21 by a set screw 61. The'saidparts 60 to 61 are best shown in Fig. 7.

The two or twin cylinder and piston motors described are arranged to beoperated by compressed air or steam, preferably the former. Through acontrol .valve and connections which will now be described, attention isdirected particularly to Figs. 7 to 16 inclusive and I la to 15ainclusive.

The control. valve is shown as made up of two detachablyv but rigidlyconnected sections 63 and 69`and. rotary or oscillatory valve head 10.The section 69 is formed with the valve cavity that contains the valvehead 10, and the section 68 is formed with. a valve seat against whichthe flat face of valve head 10 is tightly `pressed by a coil spring 1l,best shown in Fig. 8. The air receiving chamber 12 of section 69receives air under pressure from a suitable source, not shown, throughan air supply pipe 13. For oscillating the valve head 10a short stubshaft 14 is extended through and journaled in the section 68 and isprovided at its inner end with a square or' angular vshank 15 seated inthe valve. Securedto the outer end of the shaft 14 is a disclike headVor flange 16, best shown in Figs. 8 and lla to 15a inclusive.

The valve seat forming section 68 is provided with connected ports1-1-18, with connected ports.19-ll0, with connected ports 19-80 and withconnected ports 8 l-82.

The ports 11-'and 18 are connected by an'air- The ports 8| and 82 areconnectedby branch pipes 88 to the front ends of the cylinders 24through ports 89 formed in the plate 22 which, it will be remembered,affords the front end heads for the said cylinders.

The rotary valve head 10 is formed with ports 90 and 9| that extendlcompletely through the same and it is formed with a group of ports 92,93, 94, 95 and 96 that open at the face of the valve, but areinterconnected in the body of the valve. Y

A In Fig. 8 there is shown an oil cup A91, the shank of which isthreaded into the top f the case section 69 and drips oil into the airchamber 12 through a port 12.

For imparting oscillatory movements` to the disc-like ange 16 and henceto thev valve head to perform operations hereinafter traced in detail,the following connections are illustrated. A pair of links 98 arepivotally'connected by stub 99 to an outer portion'of the disc 16. The*free ends of the links 98 are connectedby links |00 to the lower endsofrods IDI, the upper `ends of which are connected to oppositely actingbell cranks |02, which, as shown, are supported from a mast |03 securedto and rising from the head 23, and braced from the rear head cylinderheads 25, by guide rods |04. The oppositely projecting arms of the bellcranks |02 are connected by rods |05 to the upper ends Vof an actuatinglever |06, which, as shown, is pivoted to the front end of a fulcrum bar|01 that is projected from the upper portion of the mast |03.

In Figs. 1, 4, 5 and 6 there is shown an electricl light bulb |08applied to the extreme front end of the trunnion 21 and covered by ashield |09 that projects the light downward into the tire. In practicethe light bulb |08 is located in a circuit I0 that includes a normallyopen push button switch having a projecting stem ||2. In Fig. 3 only apart of the circuit ||0 is shown but the manner of connecting a lightbulb to such a circuit is, of course, obvious. The body of this pushbutton is carried by the main thrust bar 21 and the stem I2 ofwhich isadapted to be engaged with the plate 26 when said bar 21 is movedforward to position the ends of the grapples 45 and 46 within theAkopening of the tire casing.

By reference to Fig. 3, it will be noted that the' outside hooks orgrapples 46 can be turned to the dotted line positions shown in Fig. 3.

Operation Under manipulationl of the control level |06 the links 98 acton .the pins II3, ||4 and ||5 of the valve connected disc 16asillustrated and best shown in Figs. 11 to 15 inclusive, Figs, 11a to15a inclusive and Fig. 16.

In Fig. 16 the neutral position of lever V'|06 is When lever |06 ismoved to position indicated f by dotted lines l2 in Fig. 16, the links98 will be as shown in Fig. 12a and said links acting 0n the pins ||3and I I4 will set the rotary valve10 in respect to its seat to aposition as shown in Fig. 12.

In this position, Fig. Y12, air under pressure is 5"! 21v to be movedrearward. 'I'his rearward movement of said primary thrust bar carriesthe in- 85 through valve port 9| and valve seat port 80 and'toipi'pes 88through valve port 90 and valve seat port 82; and this simultaneouslyintroduces air into the opposite ends of the two cylinders 24. The airintroduced into the rear ends of said cylinders prevents pistons 60 frombeing moved while the air introduced into the front ends of thecylinders causes pistonsGI tomove rearward. At the same' time thecylinder space between the pistons is openedto atmosphere through pipes84 and 83, valve seat port 18, valve ports 92 and 94 and valve seat port80' to exhaust pipe 85'. The above described movement of the pistons 6|moves cross headV 66 secondary thrust bar 50 rearward and head 5|,thereby oscillating the bell crank levers 53 and moving the plunger andthe grapples and 46 radially outward.

While the grapples 46 aremoved pivotally outward, as shown by dottedlines in Fig. 3, the tire casing is hung on the upper members of thegrapple 45, and this positions the tire casing out of line with oreccentric to the axis of the rotary head of the tire spreader. 'I'heoutward movement of the grapples just above described, however, movesthe casing from the position shown in Fig. 1 into the position shown inFig. 2, where the tire casing is then concentric to the axis of therotary head of the spreader. It has now been noted that the firstfunction of the `tire spreader.

is to'engage and center the tire casing.'

As will presently be noted, the next function i`s` to spread the tirecasing laterally and this is done by a movement of the lever |06 to theposition indicated by dotted lines marked' I3 inr Fig. 176. When thelever is moved to position I3' the valve actuating disc 16 will be movedto the position 13a and the Valve will then be set in the position shownin Fig. 13.

In the position ofthe valve 'shown in Fig. 13,

the ow of air is from supply through valve port 90, valve seat port 8|and'pipes 88 to the front ends of the two cylinders 24. At the same timethe rear ends of the cylinders will be open to exhaustv through pipes 86and 85, valve seat ports 19, valve ports 92 and 96, valve seat port 80and from thence to Aexhaust pipe 85. At this time the pipes 84 and 83are, by the valve, closed -both against admission of air and againstexhaust.

With the valve positioned as just described. ther air introduced intothe front ends of the cylinderswill simultaneosly move both of thepistons and 6| rearward. Movement of the piston 60 causes the cross head64 and main thrust bar side or rear hooks 45 rearward and away fromthe-relatively fixed outside hooks or grapples 46, and this spreads thetire casing so that it may be thoroughly inspected.

It will be understood that while the rearwardv movements of the pistons60 and 6| are simultaneously made, they will not necessarily move thesame distances.

The movement of the piston 6| causes radial outward movement of thegrapples while the movement of the piston 60 causes lateral separationof the grapples and spreading of the tires, and the amount vof saidrelative movement im- I parted to the pistons 60 and 6| will beautomatically adapted to the forces.V required to accom'-` plish the twoindependent movements.

The closing and release of the tire is performed by the followingoperations: Lever |06 is moved back past neutral or full line positionto the admitted to pipes and 63 as follows? To pipe the valve actuatingdisc 16 in the position shown in Fig. 14a thereby moving the rotaryvalve to the relativeposition shown in Fig. 14. In; the position of theparts shown in Fig. 14, air under pressure is admitted to the outer endsof the cylinders 24 as follows: Through valve port 90, valve seat port19 and pipes 85 and 86, and at the same time the rear ends of thecylinders are open to exhaust through pipes 88, valve seat port 8 I,valve ports 95 and 83 and valve seat port 80 to exhau-st pipe 85. AtYthe same time, the'cylinder space .between the pistons is opened toexhaust through pipes 84|l and 83, valve seat port 11,'valve ports 92and 93 and valve seat port 8D to exhaust pipe 85.

In the position of the valve shown in Fig. 14, the two, pistons will be;moved forward in the cylinders but will not be opened to their normalextent.A To move the two pistons to their normal positions shown in Fig.7, the lever |06 is moved to the` position shown at l in Fig. 16 therebymoving the valve actuating disc 'I6 to the position shown in Fig. a andcausing the valve 10 tobe moved to the relative position shown in Fig.15.

With the valve positioned as shown in Fig. 15, the front ends of thecylinders 24 are open to exhaust through valve seat port 82, valve ports95 and 92 to valve seat port 19 and from'thence to exhau-st pipe 85. Atthis time in the said position of the valve, air under pressure isintroduced into the cylinderspace between the pistons through valveports 90, valve seat port 18 and pipes' 83 and 84. This introductionofthe air into' cylinder space between the pistons took place while thefront ends ofthe cylinders are closed both against the exhaust and theadmission of air, and hence the introduction of air under pressure intothe cylinder Abetween the pistons while the front ends of the cylindersare open to exhaust serves to set the two` pistons in their normalpositions shown in Fig. 7. Also, it will be understood that when thepistons have been restored to their normal positions shown inA Fig. '7the" various movable parts Vof the apparatus, including the grapples orhooks 45- and 4B', will be returned to th-'e positions shown in- Fig. 1,so that thetire may be 'readily removed when the'grapples havel beenmoved pivotally outward.

Y From the foregoing it will be evident that the preferred form of themechanism described may be; modied within the scope of-l the inventionherein disclosedand claimed. In the preferred structure illustrated arotary bearing head and connections therefrom including the plungers34,A

grapple-carrying rods 36l and extensible arms 31-38 constituteV a veryeicient and-desirable form of carrier for the inner and outersets' ofgrapples.

` What I claim is:

1.v A device of the class described comprising a support, a carrierrotatably mounted on said support, inner and outer tirecasing-engaging'grapples mounted on said carrier for rotation therewithand for axial separation and for radial movements thereon, primary and`secondary thrust bars at the axisof rotation of said carrier, saidprimary bar having connections impartingV lateral separation of saidsets of grapples and said secondary thrust bar having connections forimparting radial inward and outward movements to said grapples.

2. The structure dened in claim 1 in further combination withfluid-actuated motor means for yposition indicated. at I4", in 16, andthis sets independently moving said primary and secondary thrust, bars.

3. In a device of the class described, a supporting frame, primary andsecondary thrust bars mounted for parallel sliding movements in saidframe, a bearing head carried by but journaled to the front end of saidprimary thrust bar, plungers'rnounted in said bearing ring for movementsradially thereof, a head secured to the front end of said secondarythrust bar, connections between said last noted head and said plungersVfor. imparting radial movements to the latter, means for axially movingsaid primary and thrust bar, inner and outer grapples carried by theouter ends of said plungers, both movable radially with said plungers,the inside grapples being movable withsaid plungers, bearing head andprimary thrustbar, toward and from the outer grapples, and means forholding the outer grapples against movements axially of said bearinghead.

4. The structure dened in claim 3 in which the meansfor moving saidprimary and secondary grapples includes a cylinder having two pistonswith extended rods, onepiston rod being connected to saidprimary thrustbar and the other being connected to said secondary thrust bar, andmeans for controlling admission into and exhaust of motive fluid to andfrom said cyl-inder, to accomplish the movements indicated.

5. The structure dened in claim y3 in which the connection between thehead of said thrust bar and said plungers includesbell crank leverspivoted to said rotary bearing head, and links connecting said bellcrank levers to the head of said secondary thrust barv and to therespective plungers.

6. The structure defined in claim 3. in which the means for moving said'primary and thrust bar includes a cylinder having two pistons therein,said pistons having concentric rods, the one connected to saidprim-arythrust bar and the other to said secondary thrust bar, and manuallycontrolled valve mechanism for controlling the admission andexhaust ofmotive iiuid to said cylinder to accomplish the means indicated.

'7. In a device of the class described, a supportingV frame memberhaving a hub-like portion, primary and secondary thrust bars slidablymounted in said hub-like portion, circumferentially spaced endwiseadjustable supporting arms rotating from said hubparallelcircumferentially spaced guide bars projected from the outer ends ofsaid expansible arms parallel to the axis of said hub member, a bearinghead applied to the front, end of said primary thrust bar, plungersmounted on and radiating from said .bearing head, sleeves and insidegrapples connected to the outer ends of said plungers, with said sleevesslidably mounted on said guide bars, outside grapples applied to theendsofl said guide bars, a thrust hea-d slidable on the said primary vguidebar and connected to said secondary thrust bar for sliding movementswith the latter, and connections between saidv thrust head and plungers,whereby sliding movements of said second-ary thrust bar,

in respect to said primary thrust bar, will impart.

the connections between said plungers and the thrust head of saidsecondary bar include bell cranks pivoted to said bearing head, andlinks connecting said bell cranks to said plungers and to said thrusthead.

10. The structure dened in claim 7 in which the connections between saidplungers and the thrust head of said secondary bar include bell crankspivoted to said bearing head, and links connecting said bell cranks tosaid plungers and to said thrust head, and in which said bearing head isrotatable on said primary thrust bar but movable axially therewith andsaid thrust headis rotatable around said primary thrust bar but slidablethereon under sliding movements of said secondary thrust bar.

11. The structure deiined in claim '7 in further combination withv uidpressure motor means having independent connections to said prim-ary andsecondary bars for independently sliding the same,

12. In a device of the class described, a supporting frame member havinga hub-like portion, primary and secondary thrust bars slidably mountedthrough said hub-like portion, -an annular bearing head rotatablymounted on the front end `oi said primary thrust bar, plungers radiallymovable in said bearing head, inside and outside grapples connected tothe outer ends of said plungers for radial movements toward and from theaxis of said head, and a thrust head rotatably and slidably mounted onsaid primary thrust bar and connected to said secondary thrust bar forsliding movements therewith, connections between said thrust head andsaid plungers for imparting radial movements thereto, means anchoringthe outside grapples against movements longitudinally of said thrustbars, and means for imparting independent sliding movements to saidprimary and secondary thrust bars.

13. The structure defined in claim 12 in which the connections betweensaid thrust head and plungers include bell crank levers pivoted to saidbearing head, and links connecting said bell crank levers to said thrusthead and plungers. A

14. The structure defined in claim 12 in which the means for impartingindependent endwise movements to said primary and secondary thrust barsincludes a cylinder and piston motor in which the cylinder is providedwith two pistons, one connected to said primary bar and the other tosaid secondary bar.

15. In a device of the class described, a supporting frame member havinga hub-like portion, primary and secondary thrust bars slidably mountedthrough said hub-like portion, an annular bearing head rotatably mountedon the front end of said primary thrust bar, plungers radially movablein said bearing head, a hub rotatably mounted on the hub-like portion ofsaid frame member and provided with circumferentially spaced radiallyextensible arms, circumferentially spaced parallel guide rods secured tothe outer ends of said extensible arms, sleeves slidably mounted on saidguide rods, inside grapples connected to said sleeves and the outer endsof said plungers, outside grapples secured to the extended ends of saidguide rods, said extensible arms serving t0 anchor said guide rods andoutside grapples against movement longitudinally of said thrust bars, athrust head rotatably slidably mounted on said primary thrust bar andsecured to said secondary thrust bar for sliding movements therewith,and connections between said thrust head and plungers for moving thelatter when said secondary thrust bar is moved longitudinally. 16. In adevice of the class described, .a supporting frame member having ahub-like portion, primary and secondary thrust lbars slidably mountedthrough said hub-like portion, an annular bearing head rotatably mountedon the front end of said primary thrust bar, plungers radially movablein said bearing head, a hub rotatably mounted on the hub-"like portionof said frame member and provided with circumferentially spaced radiallyextensible arms, circumferentially spaced parallel guide rods secured tothe outer ends of said extensible arms, sleeves slidably mounted on saidguide rods, inside grapples connected to said sleeves and the outer endsof said plungers, outside grapples secured to the extended ends of saidguide rods, said extensible arms serving to anchor said guide rods andoutside grapples against movement longitudinally of said thrust bars,and thrust head rotatably and slidably mounted on said primary thrustbar .and secured to said secondary thrust bar for sliding movementstherewith, bell crank levers pivoted to said bearing head and linksconnecting said bell crank levers to said plungers and lto said thrusthead.

17. The structure defied in claim l5 in further combination with powermeans for independently moving said primary and secondary thrust bar.

18. The structure dened in claim 15 in further combination with powermeans for independently moving said primary and secondary thrust bars,said power means including a cylinder having two pistons therein withconcentric piston rods, one connected to said primary thrust bar and theother connected to said secondary thrust bar.

19. The structure dened in claim 15 in further combination with powermeans for independently moving said prim-ary and secondary thrust bars,said power means including a cylinder having two pistons therein withconcentric piston rods, one connected to said primary thrust bar and theother connected to said secondary thrust bar, and fluid pressurecontrolling valve mechanism for controlling the admission and exhaust ofm0- tive uid to and from the ends and intermediate portion of saidcylinder.

GUSTAV I. ANDERSON.

